The problem that i've found is that while on the scroll i've set the scale for example 1:1 the real dimesion is not 1:1 i mean on my sketch i've for example a circle of 59mm dia, on the scroll the quote is 59dia but if i try to do a measure i see that the dia is 56.70mm. why?

i add my sketch just to give you an idea. Try to print the pdf to understand what i'm talking about.